Abstract: The substrate for diffusing volatile substances comprises a dispersible binder and a natural material, and the percentages by weight in the dry state are: dispersible binder: 15-45%; and natural material: 55-75%. It may also comprise a preservative. It provides a substrate that provides constant and durable air diffusion properties.

Abstract: The substrate for diffusing volatile substances comprises a dispersible binder and a biodegradable material, the percentages by weight on the dry state being preferably: dispersible binder: 15-45% and biodegradable material: 55-75%. It may also comprise a biodegradable preservative such as sodium benzoate. It permits to provide a biodegradable substrate to diffuse volatile substances, which has a short biodegradation time.

Abstract: The diffusion device comprises a refill (1) in which liquid containing the volatile substances is housed, the refill (1) comprising: a hole (2) for the passage of the liquid; a sealing element (3) movable between a closed position in which it prevents the passage of the liquid and an open position in which it allows the liquid to pass through the hole (2); and an elastic element (4) that presses the sealing element (3) into its closed position, wherein the sealing element (3) comprises a housing (8) for housing an activation element (7) that moves the closure element (3) from the closed position to the open position against the action of the elastic element (4). It permits to provide a device that only works when the refill is original and is inserted in the correct position.